As a non-volatile memory has an advantage that data stored therein is not disappeared after power-off, it is a necessary memory element in many electronic products for maintaining a normal operation thereof. Presently, a resistive random access memory (RRAM) is one type of the non-volatile memory that is actively developed in the industry, and since it has advantages of low writing operation voltage, short write and erase time, long retention time, non-destructive reading, multi-level capability, simple structure and small cell area, etc., it has a great application potential in future personal computers and electronic equipment.
A resistive memory cell is a memory that stores data through a resistance level, for example, a low resistance state represents logic level 0, and a high resistance state represents logic level 1. Further, if a positive voltage is applied to the resistive memory cell, the resistive memory cell can be transferred from the high resistance state to the low resistance state, which is referred to as a set operation. Conversely, if a negative voltage is applied to the resistive memory cell, the resistive memory cell is transferred from the low resistance state to the high resistance state, which is referred to as a reset operation. However, since electrical conditions of the set operation and the reset operation are different (for example, set currents are different), the set operation and the reset operation generally cannot be simultaneously applied to a plurality of resistive memory cells of a same row, which influences the write speed and the array efficiency of a resistive memory system.